I have been using lipos from way back when. The cells came in a blister pack and you had to assemble them. No balance chargers, you used the NIMH setting and had a multi meter per cell. if one cell was down you either charged it alone or replaced it.
I have yet to hear of a confirmed report of a undamaged, not over charged lipo sitting for 3 weeks suddenly going up in smoke. Always turns out, it was damaged in a crash a day, week earlier, or some other damage. They shorted the battery out when they changed the connector, shorted it when soldering the plug on, stabbed it with a knife when they were cutting the shrink wrap off. Always had some damage to it.
My batteries are stored open on a wood shelf with a piece of Hardy backer under them in the garage. Hardy Backer is a concrete board. I use a piece for my welding bench. If I do not burn through it with my welder, really doubt a lipo would hurt it. They are not packed together, they have space between them. Doubt if one did go up, it would hurt the one next to it. Oh, I have yet to have a confirmed report of a lipo actually exploding. They do not explode, they do burn very rapidly, but no KaBoom.
To date, I have had (2) lipos go up in smoke that were not due to crash damage. They went up when I plugged them the wrong way into a "Y" harness. If they are damaged, they are not kept with the rest of the lipos.
I do find it some what funny how people build bunkers, steel lockers for their lipos, yet do not think twice about the BBQ propane bottle or gas can sitting in the garage. Either of them has more potential energy stored in them.
Buzz.